Gas electric drive



April 1, 1930. F. E. QUEENEY 1,752,931

GAS ELECTRIC DRIVE Filed Oct. 11, 1926 4 Sheets-Sheet 1 CLOSE 2 AT RELA- TIA/ELY GENERA T0 H VOLT 5] mom U601 fkmwr vase/var @513 @Hiomug MIM W April 1, 1930. F. E. QUEENEY I 1,752,931

GAS ELECTRIC DRIVE Filed Oct. 11, 1926 4 Sheets-Sheet 2 Patented Apr. 1, 1930 UNHTED STATES PATENT OFFICE FRANK E. QUEENEY, OF TEANECK, NEW JERSEY, ASSIGNOR T INTERNATIONAL MQTGR COMPANY, OF IQ'EN YORK, N. Y., A CORPORATION OF DELAWARE GAS ELECTRIC DRIVE Application filed October 11, 1926.

This invention relates broadly to a drive or transmission for selt-propelled vehicles and more specifically to the disposition of circuits and their control in what is known in the trade as gas-electric drives for motor vehicles, rail cars and the like. In such vehicles an electric generator is driven by an internal combustion engine and current from the generator is utilized in one or more motors turning the driving wheels of the vehicle. Heretotore in gas-electric drives ithas not been found possible to so associate a generator and an internal combustion engine that the speed-torque curve of the generator would follow, that is, coincide closely with the power curve oi the engine, but in every instance, under certain conditions of operation the generator either overran the engine or served to retard the operation of the same. One object of the present invention is to overcome these deficiencies in operation and provide a generator whereof the speedtorque curve will .-.ib-stantially coincide with the power curve of the engine. Accordingly the chraacteristics of the generator are varied by suitable changes in the field, dependent upon the engine output so that it corresponds approximately to the power output of the engine.

Another objectof the present invention is the regulation of the engine speed to maintain it between certain predetermined points, for instance, with respect to a particular engine between the most economical speed for that engine say around 1400 R. P. M. and its maximum horsepower speed, say around 2000 R. P. M. Nit-h gas electric drives as at present constituted when a greater effort is required as the vehicle begins the ascent of a hill, there is a reduction in the engine spee because of the greater load upon the engine while the consumption of current increases.

his is due to the use of a type of winding of the generator field which does not break down the voltage sufiiciently rapidly. Thus, if the hill is steep enough or the load on the vehicle great enough the engine will die down below its most economical speed which must then be increased to a speed exceeding the maximum horse power peak to obtain the requisite generator output. Fuel is thus con- Serial No. 140,764.

sumed without return and electric heat losses generated without gain.

According to the present invention these disadvantages are eliminated and the object attained by the provision of means dependent upon the output of the generator, to maintain the engine within a predetermined speed range. More particularly, the shunt field in a compound wound generator having a cumulative series field is weakened, say, by the interposition of resistance in the shunt field circuit. This may be efiected by a series CUrrent relay operable upon a predetermined current value. The relay may also effect the energization of a teaser field circuit for the generator. Both of these operations serve to reduce the generator loading and permit thereby an increase in the engine speed.

The invention also seeks to provide a motor and associated electrical parts which shall aiiord a high starting torque and also give a higher vehicle speed at lower engine speeds. To this end a second relay serving as '2. voltage regulator may be associated with the motor which weakens the motor fields at predetermined voltages corresponding to a vehicle speed obtained with the maximum engine speed described above (i. e.) 2000 R. P. M. This relay is operated by the voltage across the generator circuit and upon a predetermined voltage opens the shunted circuit on the compound series field winding to obtain the necessary current in the shunt field by the use of the compound series windin The relay may also have a contact which closes and places a shunted resistance across the fields of a motor having a high torque ratio winding to afford a greater starting torque and also give higher vehicle speeds at lower engine speeds.

If desired the current relay may be re placed by two or more relays operable upon diiierent current values where the drop in the engine speed from the maximum to its most economical speed in one step is disadvantageous.

In order that the invention may be clearly understood reference will now be had to the accompanying drawings, illustrating preferred embodiments thereof, wherein:

Figure l'is a diagrammatic view showing a wiring diagram for a generator and motor in a gas-electric drive according to the present invention.

Figure 2 is a diagrammatic view similar to Figure 1 but showing a modification or" the wiring and the incorporation of a second current relay.

Figure 3 is a view showing a graph indicating engine performance at predetermined time intervals in a gas-electric drive according to the present invention.

Figure 4; is a view showing a graph illustrating the efi'ect of the operation of one or" the current relays upon the voltage, current and power curve of a particular gas-electric drive when the vehicle istraveling along on level ground.

, Figure 5 is a view similar to Figure 4: but showing the result obtained in climbing a hill.

Assuming now that the vehicle is stationary with the engine not in operation the engine is first started in the usual manner while the field'circuits of the generator are open. A controller, not shown, is then closed and thereby the series field is slightly energized while the shunt field has practically no ener gization; At this point the engine is idling, say, at about 250 R. P. M. In this condition to move the vehicle while the engine is throttled down, it is necessary, as is well understood, to energize the teaser field.

The tickler field winding a on the generator is availed of to give a quicker building up of the voltage as soon as the accelerator pedal is pressed. The tickler field current is supplied by the battery Z). With present drives the battery is connected all the time the engine is in operation. To save this battery current and still be ableto use a larger amperage to give a quicker pick up, an automatic switch 0 is used to close the circuit on the first predetermined movement of the accelerator pedal 0 and break the circuit again so soon as the generator voltage has built ir The particular form taken by the switch forms no part of the present invention. As illustrated it forms the subject matter of a co-pending application by the present applicant, U. S. Ser. No. 112,515 filed May 29, 1926, now Patent No. 1,646,764, dated October 25, 1927. This switch not only saves the battery current but since the circuit is normally broken no energization of the generator which would set the vehicle in motion is possible when the engine is idle as would be the case where a separate exciter wasassociated with the generator. Doing away with a separate exciter also reduces the weight of the vehicle since an exciter weighs two hundred pounds or more, its initial cost is considerable and its maintenance cost, because of the eX citer brushes and commutator is no small additional item. Furthermore by the present construction there is a gain in performance since the engine is enabled to deliver more horsepower in a given time.

Assuming now that the engine is in operation and the vehicle proceeding, the excitation of the tickler field winding having ceased, the power curve of the engine is indicated in full lines between 0 and the roman numeral 1 in Figure 3. The excitation of.

the tickler field having ceased say when the engine has attained its most economical speed of about 1400 R. M. With an increase in the work to be done as when the vehicle load is increased or a hill is to be ascenoed, the relay (Z is adapted to function. This relay is a series current relay and operates at a predetermined current value, say 165 amperes to reduce the generator loading and allow the engine to speed up and operate at a more efficient point on its power curve, say 1950 R. l M. When the current has reached the relay closing point the relay which is oper ated as will be understood by the main genera tor current closes the contacts (Z to out in the excitation of the tickler field and opens the contacts 6Z2 which results in the interposi tion of a resistance 6 through the shunt field circuit f.

l/Vhen the vehicle has arrived at the top of the hill or has accelerated so that less power is required for its propulsion relay cl drops back again closing contacts d say when the current is reduced once more to below 165 amperes, to short circuit the resistance 6. In the power curve Figure 3, the maximum horsepower speed is indicated by the full lines at the point marked by the roman numeral 11. As shown by the curve at point III the generator loading results in an increase in the engine loading which reduces the engine speed tothe most economical one say between 1200 to 1400 R. P. M.

This relay (Z also has a contact d which closes the tickler field circuit to give a stable shunt field for very heavy loads, such as climbing a steep grade when the generator is called upon to deliver a large amperage at a low voltage.

Relay 9 is incorporated for the purpose of saving from 500 to 1.000 watts in the shunt field exciting current by using the compound series winding for the necessary excitation.

There is also obtained a higher voltage at a' lower engine speed. This relay is a voltage relay and is designed to function at a voltage of 230 to open the shunted circuit he on the compound series field winding of the generator and to open the contacts 9 to interpose a resistance 2' in the shunt field f. This will also materially reduce the rise in temperature of the generator since the temperature in the shunt field is the highest due to the fact that the shunt field windings are of as low a resistance as possible to give a quick pick up.

Although generally rated at 125 volts, it is found that the voltage measures between 250 and 300 volts at high vehicle speeds. Relay 7 is also adapted to close a contact to place a shunted resistance j across the motor field 7s whi "a has a special high torque ratio winding to give a greater starting torque. This will also give higher vehicle speeds at lower engine speeds. he eii'ect of the voltage relay upon the engine power curve is illustrated in Figure 3 between the roman numerals IV and V. As the momentum of the vehicle in creases and the work to be performed by the engine and generator proportionately decreased the engine speed increases as shown by the power curve between the points III and 1V until the maximum horsepower speed of say 1950 R. P. M. is attained whereupon the relay g inter-poses the resistance 2' in the generator snunt field f and opens the shunted circuit h on the compound series field winding. In addition relay it closes the contacts g which place a shunted resistance across the motor field. The motor field is weakened at a predetermined voltage say of 230 corresponding to a vehicle speed obtained with the efficient maximum horsepower engine speed of say 1950 R. P. M. It this were not done the engine speed would exceed the maximum horsepower peak beyond which energy is wasted. It will be seen that the loading of the generator and the motor causes a decr ase in the engine speed from the points TV to V at which latter pointthe characteri tic of the power curve appro shes the economical engine speed. Upon a reduction in the voltage say to 200 volts relay g is no longer energizes, thecontacts g and are closed and the contacts g opened which short circuits the resistance 2' and opens the shunted circuit The power curve for the particular internal combustion engine under consideration is in dicated in full lines in Figure 3. t will be observed that, through the instrumentality or" the relays, the actual power curve for the engine is maintained between the predetermined maximum and minimum engine R. P. M. By the interposition of additional series current relays the characteristics of the actual power curve may be smoothed out considerably. This is accomplished by doing in two steps what was neretofore done in one. In Figure 3 a power curve is shown in dotted lines illustrating the characteristics of the engine with two series current relays Z and m interposed in the electrical circuits instead of the one described. Such a wiring diagram is shown in Figure 2.

Relay Z is also operated by the main generator current, being provided with a series coil. It opens the contacts Z at a predetermined current, say 150 amperes, thereby interposing the resistance it through the shunt field circuit and thus reducing the generator loading and allowing the engine to speed up and operate at a more efficient point in its power curve, somewhat around 1700 R. P. M. This increase in engine speed is indicated in the graph in Figure 3 by the power curve shown in dotted lines between the point 1, where the relay Z operates, and the point 2. lVhen the current is reduced, less power being required for any reason, the relay closes, short circuiting the resistance nand again creating a full shunt field for the generator and thereby loading up the engine and reducing its speed as shown by the curve 23 to approximately that of the ideal power curve. During this period, of course, the contacts m are closed to complete the shunt field circuit. Should more power be required, as when a heavy grade is to be ascended, the second relay m is adapted to operate. This relay also has a series coil and is operated by the main generator current when that current value reaches say 200 amperes. At such a current value the contacts m are opened thereby interposing the resistance a in the shunt field circuit to weaken the shunt field and in addition closes the contact m of the teaser field circuit a. Through the instrumentality of a weakened shunt field and the energization of the teaser field winding a, a stable shunt field is availed of for very heavy loads. Thus the characteristic of the engine power curve which at the instant the relay m operates may be indicated by the point 3 are enabled to change as shown by the dotted line 34, the engine speeding up to its maximum efficient speed say around 1700 R. P. M. as shown by the ordinate of the point at in the graph, Figure 3. When the current is reduced below 200 amperes as when the work required of the drive is less the relay m again opens, closing the contacts of to short circuit the resistance n and permit the generator to again operate with a shunt field of full strength. The operation of the motor relay, and the voltage relay, is as described hereinbefore.

Figures at and 5 illustrate the current, engine power and voltage curves from the vehicle at rest to a point just beyond the operation of the current relay, Figure 5 being with respect to the operation of the transmission when the vehicle is on a level and Figure 4 when the vehicle is ascending a grade. The figures have been inserted for reference in an understanding of the operation just described.

It will thus be seen that a transmission for gas-electric driven vehicles has been provided in which the engine and generator are automatically co-ordinated in order that the engine may at all times operate at its most efficient point.

Various modifications may be made in the characteristics and number of the elements going to make up the controlling devices as a whole dependent upon the units with which th'ey are associated and no limitation is intended by the foregoing description or accom panying illustrations except as indicated in the appended claims.

What is claimed is:

1. In a drive for motor vehicles, in combination, an engine, a generator driven thereby, a motor and means operable upon a predetermined excess voltage to Weaken the motor field and upon a predetermined minimum voltage to strengthen the field, whereby the engine speed is maintained Within a predetermined range dependent upon the voltage oil of the motor.

2. Ina drive for motor vehicles, in combination, an engine, a compound Wound generator having an accumulative series field, an auxiliary exciting means, a motor, means to Weaken the shunt field circuit of the generator dependent upon the value of the current delivered to the motor, and means simultaneously to cause the generator to be excited by the auxiliary means.

3. In a drive for motor vehicles, in combination,ian engine, a compound wound generator having a shunt field, an accumulative series field, and a teaser field Winding, a motor, aresistance, a source of electrical energy for the teaser field, and a current relay having a coil in series With the main generator circuit and operable to interpose the resistance in the shunt field circuit and energize the teaser field upon a predetermined current value.

4. In a drive for motor vehicles, in combination, an engine, a compound Wound generator having a shunt field and an accumulative series field, a motor, means to vary the excitation of the series field at a predetermined Voltage of the generator, and means to Weaken theshunt field upon a predetermined voltage output of the generator.

5. In a drive for motor vehicles,-in combination, an engine, a compound Wound generatorhaving a shunt field and an accumulative series field, a motor, means to vary the excitation of the series field at a predetermined vol"- age of the generator, a resistance and a relay operable upon a predetermined voltage output of the generator to interpose the resistance in the shunt field circuit. 7

6.. In a drive for motor vehicles, in combination, an engine, a compound Wound generator having an accumulative series field, a motor, a resistance circuit shunted across the series field, a relay operable upon a predetermined voltage, and contacts carried thereby to open the shunted resistance circuit upon operation of the relay.

7. In a drive for motor vehicles, in combination, an engine, a generator, a motor having aseries field Winding, a resistance circuit and a relay operable upon a predetermined voltage to connect the resistance circuit across the motor field.

8. In a drive for motor vehicles, in combination, an engine, a compound Wound generator having a shunt field, an accumulative series field, and a teaser field Winding, a source of electrical energy, an accelerator pedalfor the engine and means to connect the source of electrical energy With the teaser field throughout a predetermined movement of the accelerator pedal.

9. In a drive for motor vehicles, in combination, an engine, a compound Wound generator having a shunt field, an accumulative series field, and a teaser field Winding, a motor having a high torque ratio Winding, a resistance circuit for the motor field, a source of electricalenergy, a resistance circuit, a series relay operable upon a predetermined current value in the generator circuit, contacts operated by the relay to interpose the second resistance circuit in the generator shunt field and to connect the source of energy with the teaser field, a third resistance circuit, and a second relay operable upon a predetermined voltage off of the generator, contacts oper ated by the relay to interpose the third resistance circuit in the generator shunt field, and place the first resistance circuit across the motor field.

10. In a drive for motor vehicles in combination, an engine, a generator, driven thereby, series and shunt fields for the generator, a motor, a field for the motor and means operable upon a predetermined excess voltage to Weaken the motor field and generator shunt field and strengthen the generator series field, and upon a predetermined minimum voltage to strengthen the first two and Weaken the last, whereby the engine speed is maintained Within a predetermined range depedent upon the voltage of the motor.

11. In a drive for motor vehicles, in combination, an engine, a compound Wound generator having a shunt field, an accumulative series field, and a teaser field Winding, a source of electrical energy, an accelerator pedal for the engine, means to connect the source of energy With the teaser field throughout a predetermined movement of the accelerator pedal, and auxiliary means to connect the source to the teaser field upon a predetermined generator current.

This specification signed this 7th day of October A. D. 1926.

FRANK E. QUEENEY. 

